Two way envelopes which eliminate the need for enclosing a return envelope to facilitate replying to the original sender are well-known. The advent of the window envelope, automatic letter openers, electronic mail sorting and the use of one or more insertions of advertising material within the envelope by the original sender has made most prior art two way envelopes inadequate. Where the prior art envelopes have consisted of a large number of panels, flaps and tabs the cost of manufacture and the amount of paper used for each envelope has almost equalled, or even exceeded, the savings possible by eliminating the need for the enclosure of return envelopes in mailing pieces.
Highly complicated two way envelopes have been difficult for many recipients to master, requiring elaborate instructions printed on the outside of these envelopes together with illustrations showing how to place the envelope in condition for reuse.
In order to cover the window aperture on the front of the envelope and also any Data Processing Information that may be required by the Postal Authorities, the return flap of prior art two way envelopes such as are shown in the Steinke U.S. Pat. No. 1,145,935 must be of a length which will extend almost to the bottom of the front of the envelope when used for resealing purposes. As a result, withdrawing the return flap often causes the flap to be destroyed as it is pulled out of the envelope enclosure. Since the return flap is almost coextensive with the interior of the envelope, it is often unnoticed and the recipient fails to understand how to make a return envelope out of the opened envelope which has been received.
Accordingly, it is an object of the present invention to provide simplified two way envelopes which lend themselves to manufacture on high speed web-type envelope making machines and which overcome the disadvantages of prior art envelopes.
Another object of the present invention is to provide a two way envelope which will not be destroyed if opened in any of the customary ways by the recipient. A further object of the present invention is to provide a two way envelope which will automatically convert into its return mode by the simple action of normal opening of the envelope following its initial receipt.
A further object of the present invention is to provide a two way envelope which is compatible with window type envelopes while at the same time maintaining the security of the contents on remailing.
Still another object of the present invention is to provide two way envelopes which lend themselves to automatic insertion of enclosures and eliminate the need for enclosing self-addressed envelopes.